1. Field of the Invention
Exemplary embodiments of the present invention relate to a fan clutch and, more particularly, to an variable channel type fan clutch that automatically blocks an oil return hole that is a path for return and circulation of oil when an engine is stopped and when the fan clutch exceeds an operation temperature, thereby improving a cold start characteristic of the engine and operability of the fan clutch.
2. Description of Related Art
In general, a fan clutch constituting an engine cooling system along with a radiator and a cooling fan controls revolutions per minute (rpm) of the cooling fan depending on a temperature of cooling water.
Typically, the fan clutch is stopped when an engine is stopped, and is selectively driven depending on the temperature of the cooling water when the engine is driven. In this way, the fan clutch cooperates with the engine
To this end, the fan clutch forms an oil circulating structure in which internal storage and operational chambers lead to an oil return hole, transmits a rotational force of a rotor based on a fluid viscous frictional force of the oil circulating therein, and has a valve for opening/closing an oil channel.
However, since the oil return hole of the fan clutch is controlled in a normally open mode, the oil has no way of flowing from the storage chamber to the operational chamber through the oil return hole even when the engine is stopped.
When the oil flows through the oil return hole, the oil flows at a low or high flow rate depending on a position of the oil return hole when the engine is stopped. In either case, when the engine is restarted, the fan clutch and the cooling fan are unnecessarily engaged due to the oil existing in the operational chamber.
Especially, this engagement leads to reducing a cold start characteristic and a start acceleration characteristic, and results in generating noise of the cooling fan.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.